// SHA1.cpp: implementation of the CSHA1 class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "SHA1.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CSHA1::CSHA1()
{
	Reset();
}

CSHA1::~CSHA1()
{
	
}

/*	
*	Reset
*
*	Description:
*		This function will initialize the sha1 class member variables
*		in preparation for computing a new message digest.
*
*	Parameters:
*		None.
*
*	Returns:
*		Nothing.
*
*	Comments:
*
*/
void	CSHA1::Reset()
{
	Length_Low			= 0;
	Length_High			= 0;
	Message_Block_Index	= 0;
	
	H[0]		= 0x67452301;
	H[1]		= 0xEFCDAB89;
	H[2]		= 0x98BADCFE;
	H[3]		= 0x10325476;
	H[4]		= 0xC3D2E1F0;
	
	Computed	= false;
	Corrupted	= false;
}

/*	
*	Result
*
*	Description:
*		This function will return the 160-bit message digest into the
*		array provided.
*
*	Parameters:
*		message_digest_array: [out]
*			This is an array of five unsigned integers which will be filled
*			with the message digest that has been computed.
*
*	Returns:
*		True if successful, false if it failed.
*
*	Comments:
*
*/
bool	CSHA1::Result(unsigned int *message_digest_array)
{
	int i;									// Counter
	
	if (Corrupted)
	{
		return false;
	}
	
	if (!Computed)
	{
		PadMessage();
		Computed = true;
	}
	
	for(i = 0; i < 5; i++)
	{
		message_digest_array[i] = H[i];
	}
	
	return true;
}

/*	
*	Input
*
*	Description:
*		This function accepts an array of octets as the next portion of
*		the message.
*
*	Parameters:
*		message_array: [in]
*			An array of characters representing the next portion of the
*			message.
*
*	Returns:
*		Nothing.
*
*	Comments:
*
*/
void	CSHA1::Input(	const unsigned char	*message_array,
		  unsigned 	int		length)
{
	if (!length)
	{
		return;
	}
	
	if (Computed || Corrupted)
	{
		Corrupted = true;
		return;
	}
	
	while(length-- && !Corrupted)
	{
		Message_Block[Message_Block_Index++] = (*message_array & 0xFF);
		
		Length_Low += 8;
		Length_Low &= 0xFFFFFFFF;				// Force it to 32 bits
		if (Length_Low == 0)
		{
			Length_High++;
			Length_High &= 0xFFFFFFFF;			// Force it to 32 bits
			if (Length_High == 0)
			{
				Corrupted = true;				// Message is too long
			}
		}
		
		if (Message_Block_Index == 64)
		{
			ProcessMessageBlock();
		}
		
		message_array++;
	}
}

/*	
*	Input
*
*	Description:
*		This function accepts an array of octets as the next portion of
*		the message.
*
*	Parameters:
*		message_array: [in]
*			An array of characters representing the next portion of the
*			message.
*		length: [in]
*			The length of the message_array
*
*	Returns:
*		Nothing.
*
*	Comments:
*
*/
void	CSHA1::Input(	const char	*message_array,
		  unsigned int	length)
{
	Input((unsigned char *) message_array, length);
}

/*	
*	Input
*
*	Description:
*		This function accepts a single octets as the next message element.
*
*	Parameters:
*		message_element: [in]
*			The next octet in the message.
*
*	Returns:
*		Nothing.
*
*	Comments:
*
*/
void	CSHA1::Input(unsigned char message_element)
{
	Input(&message_element, 1);
}

/*	
*	Input
*
*	Description:
*		This function accepts a single octet as the next message element.
*
*	Parameters:
*		message_element: [in]
*			The next octet in the message.
*
*	Returns:
*		Nothing.
*
*	Comments:
*
*/
void	CSHA1::Input(char message_element)
{
	Input((unsigned char *) &message_element, 1);
}

/*	
*	operator<<
*
*	Description:
*		This operator makes it convenient to provide character strings to
*		the SHA1 object for processing.
*
*	Parameters:
*		message_array: [in]
*			The character array to take as input.
*
*	Returns:
*		A reference to the SHA1 object.
*
*	Comments:
*		Each character is assumed to hold 8 bits of information.
*
*/
CSHA1&	CSHA1::operator<<(const char *message_array)
{
	const char *p = message_array;
	
	while(*p)
	{
		Input(*p);
		p++;
	}
	
	return *this;
}

/*	
*	operator<<
*
*	Description:
*		This operator makes it convenient to provide character strings to
*		the SHA1 object for processing.
*
*	Parameters:
*		message_array: [in]
*			The character array to take as input.
*
*	Returns:
*		A reference to the SHA1 object.
*
*	Comments:
*		Each character is assumed to hold 8 bits of information.
*
*/
CSHA1&	CSHA1::operator<<(const unsigned char *message_array)
{
	const unsigned char *p = message_array;
	
	while(*p)
	{
		Input(*p);
		p++;
	}
	
	return *this;
}

/*	
*	operator<<
*
*	Description:
*		This function provides the next octet in the message.
*
*	Parameters:
*		message_element: [in]
*			The next octet in the message
*
*	Returns:
*		A reference to the SHA1 object.
*
*	Comments:
*		The character is assumed to hold 8 bits of information.
*
*/
CSHA1&	CSHA1::operator<<(const char message_element)
{
	Input((unsigned char *) &message_element, 1);
	
	return *this;
}

/*	
*	operator<<
*
*	Description:
*		This function provides the next octet in the message.
*
*	Parameters:
*		message_element: [in]
*			The next octet in the message
*
*	Returns:
*		A reference to the SHA1 object.
*
*	Comments:
*		The character is assumed to hold 8 bits of information.
*
*/
CSHA1&	CSHA1::operator<<(const unsigned char message_element)
{
	Input(&message_element, 1);
	
	return *this;
}

/*	
*	ProcessMessageBlock
*
*	Description:
*		This function will process the next 512 bits of the message
*		stored in the Message_Block array.
*
*	Parameters:
*		None.
*
*	Returns:
*		Nothing.
*
*	Comments:
*		Many of the variable names in this function, especially the single
*	 	character names, were used because those were the names used
*	  	in the publication.
*
*/
void	CSHA1::ProcessMessageBlock()
{
	const unsigned int K[] = 	{ 				// Constants defined for SHA-1
		0x5A827999,
			0x6ED9EBA1,
			0x8F1BBCDC,
			0xCA62C1D6
	};
	int 		t;							// Loop counter
	unsigned int 	temp;						// Temporary word value
	unsigned int	W[80];						// Word sequence
	unsigned int	A, B, C, D, E;				// Word buffers
	
								/*
								*	Initialize the first 16 words in the array W
	*/
	for(t = 0; t < 16; t++)
	{
		W[t] = ((unsigned int) Message_Block[t * 4]) << 24;
		W[t] |= ((unsigned int) Message_Block[t * 4 + 1]) << 16;
		W[t] |= ((unsigned int) Message_Block[t * 4 + 2]) << 8;
		W[t] |= ((unsigned int) Message_Block[t * 4 + 3]);
	}
	
	for(t = 16; t < 80; t++)
	{
		W[t] = CircularShift(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
	}
	
	A = H[0];
	B = H[1];
	C = H[2];
	D = H[3];
	E = H[4];
	
	for(t = 0; t < 20; t++)
	{
		temp = CircularShift(5,A) + ((B & C) | ((~B) & D)) + E + W[t] + K[0];
		temp &= 0xFFFFFFFF;
		E = D;
		D = C;
		C = CircularShift(30,B);
		B = A;
		A = temp;
	}
	
	for(t = 20; t < 40; t++)
	{
		temp = CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[1];
		temp &= 0xFFFFFFFF;
		E = D;
		D = C;
		C = CircularShift(30,B);
		B = A;
		A = temp;
	}
	
	for(t = 40; t < 60; t++)
	{
		temp = CircularShift(5,A) +
			((B & C) | (B & D) | (C & D)) + E + W[t] + K[2];
		temp &= 0xFFFFFFFF;
		E = D;
		D = C;
		C = CircularShift(30,B);
		B = A;
		A = temp;
	}
	
	for(t = 60; t < 80; t++)
	{
		temp = CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[3];
		temp &= 0xFFFFFFFF;
		E = D;
		D = C;
		C = CircularShift(30,B);
		B = A;
		A = temp;
	}
	
	H[0] = (H[0] + A) & 0xFFFFFFFF;
	H[1] = (H[1] + B) & 0xFFFFFFFF;
	H[2] = (H[2] + C) & 0xFFFFFFFF;
	H[3] = (H[3] + D) & 0xFFFFFFFF;
	H[4] = (H[4] + E) & 0xFFFFFFFF;
	
	Message_Block_Index = 0;
}

/*	
*	PadMessage
*
*	Description:
*		According to the standard, the message must be padded to an even
*		512 bits.  The first padding bit must be a '1'.  The last 64 bits
*		represent the length of the original message.  All bits in between
*		should be 0.  This function will pad the message according to those
*		rules by filling the message_block array accordingly.  It will also
*		call ProcessMessageBlock() appropriately.  When it returns, it
*		can be assumed that the message digest has been computed.
*
*	Parameters:
*		None.
*
*	Returns:
*		Nothing.
*
*	Comments:
*
*/
void	CSHA1::PadMessage()
{
/*
*	Check to see if the current message block is too small to hold
*	the initial padding bits and length.  If so, we will pad the
*	block, process it, and then continue padding into a second block.
	*/
	if (Message_Block_Index > 55)
	{
		Message_Block[Message_Block_Index++] = 0x80;
		while(Message_Block_Index < 64)
		{
			Message_Block[Message_Block_Index++] = 0;
		}
		
		ProcessMessageBlock();
		
		while(Message_Block_Index < 56)
		{
			Message_Block[Message_Block_Index++] = 0;
		}
	}
	else
	{
		Message_Block[Message_Block_Index++] = 0x80;
		while(Message_Block_Index < 56)
		{
			Message_Block[Message_Block_Index++] = 0;
		}
		
	}
	
	/*
	*	Store the message length as the last 8 octets
	*/
	Message_Block[56] = (Length_High >> 24) & 0xFF;
	Message_Block[57] = (Length_High >> 16) & 0xFF;
	Message_Block[58] = (Length_High >> 8) & 0xFF;
	Message_Block[59] = (Length_High) & 0xFF;
	Message_Block[60] = (Length_Low >> 24) & 0xFF;
	Message_Block[61] = (Length_Low >> 16) & 0xFF;
	Message_Block[62] = (Length_Low >> 8) & 0xFF;
	Message_Block[63] = (Length_Low) & 0xFF;
	
	ProcessMessageBlock();
}


/*	
*	CircularShift
*
*	Description:
*		This member function will perform a circular shifting operation.
*
*	Parameters:
*		bits: [in]
*			The number of bits to shift (1-31)
*		word: [in]
*			The value to shift (assumes a 32-bit integer)
*
*	Returns:
*		The shifted value.
*
*	Comments:
*
*/
unsigned	CSHA1::CircularShift(int bits, unsigned int word)
{
	return ((word << bits) & 0xFFFFFFFF) | ((word & 0xFFFFFFFF) >> (32-bits));
}

char*	CSHA1::ClearZeroChar(char* inStr, int inLen, int& outLen)
{
	int i = 0;
	int len = inLen + 1;
	outLen = len;
	char* ret = new char[outLen];
	
	if(inLen>1)
	{
		for (i=0;i<inLen;i++)
		{
			if ('0'!=inStr[i])
			{
				break;
			}
			else
			{
				outLen = len - i - 1;
				
				if (ret)
				{
					delete[] ret;
					ret = 0;
				}
				
				ret = new char[outLen];
			}
		}
		
		char* p = inStr;
		p = p + (len-outLen);
		memcpy(ret, p, outLen);
		ret[outLen-1] = '|';
	}
	else if(1==inLen)
	{
		ret[0] = inStr[0];
		ret[1] = '|';
	}
	
	return ret;
	
}
